The present invention relates to an apparatus and method for use in medical imaging. More particularly, the present invention relates to apparatus and method for positioning a patient and/or a secondary imaging coil inside a primary imaging coil.
In magnetic resonance imaging, a patient is placed inside a coil (the "primary" coil) which is large enough in diameter to receive the patient while he is lying prone on a table slidable into and out of the coil. A selected portion of the patient is then imaged by the use of electromagnetic radiation from the primary coil.
It is known to place smaller coils, called surface or volume coils, in close proximity to the specific part of the patient to be imaged, such as the neck, spine, or knee. These coils, referred to herein as secondary coils, are used to increase resolution by having a coil closer to the part to be imaged. It is essential to place the secondary coil in a particular orientation relative to the electromagnetic field generated by the primary coil.
Current imaging systems can only take images while a patient is in one particular position. One known device allows the patient to move his knee joint to different selected positions while the patient is in the primary coil. This device requires the patient to lie face down in the primary coil, which is extremely uncomfortable for the extended period of time required to image properly, especially in the close, almost claustrophobic confines of a primary MRI coil.